Overall differences between Roman and Greek gods
It is important to recognize that the very early gods of the Romans were entirely different from those of the Greeks.
Through cultural exchanges and especially after the Roman Republic conquered Greece, the Roman gods assimilated the characteristics of the Greek pantheon since Greek culture was seen as more refined and elevated.
Compared to Roman gods, Greek gods were thorough individuals with complete personalities, with characters as complete as any historical persons, showing all the human emotions as well as divine powers.
For instance, Greek gods often participated in the affairs of humans. A testament of this is Zeus having affairs with innumerable women, or how the Greek gods used their powers to scheme against each other, using humans as pawns in their games.
The Roman gods did not, originally, have human personalities, and thus had no myths attached to them. In a way they were no more real than the supernatural forces associated with natural phenomena: rivers, mountains, trees and so on.
Instead, Roman gods had clearly defined functions: Mars was the god of war while Vulcan the god of fire.
However, they did not have wives and families, amorous escapades, fits of jealousy, or any of the other attributes of the Olympian family.
Jupiter, the chief Roman god, was in origin a rather insignificant deity, perhaps nothing more than a stone, dating from a time before the use of metals when all useful objects were made of stone.
Jupiter was, like Zeus, a sky god, or god of light, and was associated with the weather, especially thunderstorms.
He was the protector of the Latin race and of the family. Juno, his consort, the protector of women, was associated particularly with marriage and child-bearing. She was originally a Moon goddess.
There is nothing very strange in that in view of the fact that the Romans did not anthropomorphize their gods as the Greeks did.
That they failed to do so does not mean that the Romans were less religious than the Greeks. Some people would argue, on the contrary, that the Roman idea of “numen” was spiritually a finer conception than the humanized deities of Greece.
“Numen” implies vitality, and could be possessed by what we would describe as inanimate objects, as an example boundary stones.
What the early Romans really worshipped were not gods in the Greek sense, but numina, spiritual vitalities performing very specific functions.
Thus, the entrance to a temple, for example, was guarded by three numina: the threshold, the door, and the hinge of the door.
These countless numina had names and functions, but nothing much else. Spinensis, for example, helped farmers clear their fields of thorns; Cloacina, later absorbed by Venus (Aphrodite), looked after the drains.
Zeus and Jupiter have different mythological origins
What did Jupiter look like to his earliest worshippers? At first, he was neither godlike nor human: he was just an old stone, Jupiter Lapis.
A clue for this humble origin is that in the temple of Jupiter Feretrius were preserved some ancient flint-stones.
To bind himself by the strongest possible oath a man would say:
“If I knowingly deceive, may Jupiter, without harm to the City or the citadel, cast me forth as I cast this stone, hurling it as far as he could.”
Even more striking was the ceremony for ratifying a treaty, because here the whole state was involved.
One of the Fetiales, the ancient college of twenty priests who advised on international affairs, killed a pig with a flint-stone from the same shrine and said:
“If the Roman People shall be the first to transgress this treaty by common consent, and of malice aforethought, then Jupiter do you on that day strike the Roman People even as on this day I smite this pig, and smite it harder, because you are stronger and more mighty.”
Clearly the stone (or stones, for so holy an object must have been supplied with reserves) was older than Jupiter.
It goes back to neolithic days, perhaps even before them, the stones being no doubt old flint knives or axe-heads.
When the metal-users arrived they associated these venerable and rather terrifying stones with the greatest deity they knew, the god of light, Jupiter, who among other functions was the punisher of liars and law breakers.
By the time Rome had become an imperial power, Jupiter had become assimilated to the Greek Zeus, and had taken on much of his glory; but his origins were humble enough.
Although the name Zeus perhaps originally denoted “sky,” it is only very rarely that Zeus is connected with any kind of astronomical object, be it the Sun or other stars.
At first, the Greeks probably regarded Zeus as the source of all light, that of the heavenly bodies included, and this is likely why there was no well-developed native cult of the sun, the moon or the stars among the Greeks.
It is in his meteorological functions that Zeus is preeminent in the sky. The rain descends from the sky; therefore, it is Zeus the “cloud-gatherer” who dispenses it, and Theokritos mentions the “rain of Zeus,” while “Zeus rains” was a popular Greek saying.
It was quite natural, then, for the demon of the magic rain stones of primitive communities to be confused and even identified with Zeus, and the story of the stone which Rhea gave Kronos to swallow was doubtless derived from some magic rain-making ritual.
Now in order to influence the great weather spirit with an immediate directness one must get as close to him as possible; and what could be nearer to him than the mountains?
Thus, the frequency with which we find the cults of Zeus on mountain-peaks. On Dikte and Ida in Crete, on Olympus in Thessaly, on Lykaios in Arkadia, or on Kithairon in Boiotia, while such general nicknames for Zeus as “Highest”, “of the peaks “, and “of the summits” point to his association with great elevations in general.
Jupiter and Zeus are both supreme deities
As he had pre-eminence over all the other gods, the Romans gave Jupiter the title of Optimus Maximus, in other words, the Good and the Great, a designation which was to be carried over into Christianity and appears on many a monumental inscription, often abbreviated to D.O.M., Deo Optimo Maximo.
Jupiter was the god of light and sky who in time became the great protector of city and state.
Zeus is the supreme ruler of all Greek gods. He was Lord of the Sky, the Rain-god and the Cloud-gather, who wielded the awful thunderbolt. His power was greater than that of all the other divinities together.
In the Iliad he tells his family,
“I am mightiest of all. Make trial that you may know. Fasten a rope of gold to heaven and lay hold, every god and goddess. You could not drag down Zeus. But if I wished to drag you down, then I would. The rope I would bind to a pinnacle of Olympus and all would hang in air, yes, the very earth and the sea too.”
Jupiter and Zeus have similar powers over the elements
Jupiter was a god of the elements, sometimes called Dovis Pater, a name that was contracted to Diospiter, signifying “father” or “master of the sky.”
The Romans, who were always practical, worshipped him in this capacity as the god of rain, wind, thunder and lightning, which had beneficial or harmful effects on agriculture.
To designate him as such, the Romans gave Jupiter nicknames with obvious meanings such as Pluvius (Rain), Fulgurator (Lightning) , Tonitrualis (Thunder), Tonans and Fulminator (Thunder and Lightning).
Zeus is god of the thunder and lightning as well as of the rain.
At Mantineia and Olympia he was the lightning itself and not the directing agent, and with the poets he is the “Mighty Thunderer” and the “Hurler of Lightning.”
The lightning and the thunderbolts forged by his smiths, the Cyclopes, were used to overthrow the Titans.
Zeus was also the god of fertility. It was but an easy step for the god of the rain and the dew to become the god of the fertility produced by these forms of moisture.
It seemed to the Greek that since water is a fertilizing substance or vital principle and it fell upon the receptive soil, and who but Zeus was the giver of it?
It entered into plants from the soil and into animals and men from plants, so that the whole cycle of life was dependent on Zeus, who was the great “Begetter.”
Jupiter determines what happens. Zeus cannot control Fate.
According to the belief of the Romans, Jupiter determined the course of all earthly affairs, and revealed the future through signs in the heavens and the flight of birds; hence they are called his messengers.
He also revealed the future of men, through his priests known as augurs, who read messages from Jupiter in the many signs beheld in the sky, especially in the flight of birds.
More than for the Greeks, he was the god who determined the destiny of humanity, and imposed his sovereign will upon events.
For the same reason, Jupiter was invoked at the beginning of every undertaking, together with Janus, who blessed the beginning itself.
Rams were sacrificed to him on the ides of every month, and the beginning of every week. It may be remarked, in general, that the first day of every period of time, both at Rome and in Latium, was sacred to Jupiter, and marked by festivals, sacrifices, and libations.
Similarly, he was called Prodigalis, because he called forth miracles upon the earth, as lucky or unlucky signs.
Whenever the Romans made a decision about sacred or profane matters, they invoked Jupiter because the god of Gods was the source of all human activities.
In the fifth century the idea rapidly gained currency that there was a power, called Fate, that preformed the future and to which Zeus himself must bow.
As such, Zeus was not omnipotent or omniscient and could be opposed and deceived. Poseidon dupes him in the Iliad and so does Hera. Sometimes, too, the mysterious power, Fate, is spoken of as stronger than he.
Hera even asks him scornfully if he proposes to deliver from death a man Fate has doomed.
Jupiter: protector of Rome and god of justice. Zeus: protector of mankind in general and the Universe
Jupiter was considered the prime protector of Rome and its empire, and in this capacity, he played a political role which the two consuls [elected rulers during the Roman Republic], who assumed their duties each year, acknowledged by officially worshipping him.
An ancient jewel quietly shows Jupiter looking into the universe, holding the thunder in his right hand, and in his left, the imperial scepter, with the eagle at his feet.
The Jupiter Capitolinus, who was esteemed the great guardian of the Romans, and who was (according to a very early and strong notion among them) to give them the empire of the world. They called him Optimus Maximus, or the best and greatest.
Jupiter was considered as the guardian of law and the protector of justice and virtue. He maintained the sanctity of an oath, and presided over all transactions that were based upon faithfulness and justice.
Zeus, who was the “Father of gods and men,” chiefly in a spiritual and moral sense was the ultimate court of appeal for offences against the gods and the higher law, and the final arbiter of punishments.
With the Great Flood, Zeus punished mankind for their impiety; to Lykaon’s sons he meted out death for their wickedness, and Lykaon himself he changed into a wolf for having dared to trick a deity.
After he had condemned men to earn their bread by the sweat of their brow, none else could alter the decree.
Because Tantalos and Sisyphos abused their endowment of knowledge almost divine he imposed on them terrible penalties in Hades, while Prometheus suffered untold agonies for trespassing on the divine prerogative to fire and for his gratuitous enlightenment of the race of men.
In both myth and cult Zeus was the ideal statesman of the Greeks, having had that serenity of judgment which awakens the confidence of the governed.
His lordship over himself inspired self-control in those who looked up to him, and the very stains upon his dignity which the myths often revealed gave the legends an air of convincing reality.
Yet in spite of his generally accepted high political estate, we rarely meet with the cult of Zeus Panhellenios – the Zeus of the United States of Greece, so to speak – because of the Greeks’ keen sense of local independence never allowed them to realize this ideal in politics.
He frequently appeared, however, as the guardian of the family property, of boundaries, of wealth, of the domestic and state hearths, and of tribal and family kin; and he was also the patron of the higher social interests collectively and separately, of freedom, of the centralized union of tribes and brotherhoods, and of good understanding among the people.
Zeus had a human personality, Jupiter did not.
Although Jupiter heavily assimilated concepts from Zeus, he is far more detached from the affairs of humans compared to Zeus.
Jupiter intervened in the world, and on behalf of Romans, more by controlling Fate rather than as an active, visible participant.
Jupiter also did not have the pronounced penchant for women the same way Zeus did, perhaps a testimony to the more buttoned-up Roman temperament in such matters.
Zeus is most frequently represented as feeling in himself the fullness of his authority, and delighting in the consciousness of his power.
Throughout Greek mythology, he makes his presence felt and is an active participant in the affairs of humans – especially when it comes to women.
He is represented as falling in love with one woman after another and descending to all manner of tricks to hide his infidelity from his wife.
The explanation why such actions were ascribed to the most majestic of the gods is, the scholars say, that the Zeus of song and story has been made by combining many gods.
When the worship of Zeus spread to a town where there was already a divine ruler the two were slowly fused into one. The wife of the early god was then transferred to Zeus.
The result, however, was unfortunate and the later Greeks did not like these endless love affairs.
Jupiter is a god of war, Zeus is not
When victorious generals returned to Rome in triumph, they always made a solemn procession along the Appian Way to the temple of Jupiter to perform acts of thanks giving.
As a result, Jupiter was the supreme head of the Roman armies and the commanders-in-chief were merely his representatives.
He was designated at the time by the laudatory epithets of Imperator, the Commander-in-chief, Victor, the Victorious, Invictus, the Invincible, Stator, the Guardian-Founder, Opitulus, the Helpful, Feretrius,the Conqueror, Praedator, the Lover of Spoils, Triumphator, the Triumphant, and many others.
While Zeus was sometimes qualified by epithets like “War-Lord” and “Bearer of Victory,” he was very rarely known purely as a god of war, a testimony to the advanced character of the Greek religion.